Possibilities without possible worlds/histories

Tomasz Placek (Jagiellonian University, Kraków) gives a talk at the MCMP Colloquium titled "Possibilities without possible worlds/histories". Abstract: Possible worlds have turned out to be a particularly useful tool of modal metaphysics, although their globality makes them philosophically suspect. Hence, it would be desirable to arrive at some local modal notions that could be used instead of possible worlds. In this talk I will focus on what is known as historical (or real) modalities, an example of which is tomorrow's sea-battle. The modalities involved in this example are local since they refer to relatively small chunks of our world: a gathering of inimical fleets on a bay near-by has two alternative possible future continuations: one with a sea-battle and the other with no-sea battle. The objective of this talk is to sketch a theory of such modalities that is framed in terms of possible continuations rather than possible worlds or possible histories. The proposal will be tested as a semantic theory for a language with historical modalities, tenses, and indexicals.